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-rw-r--r--Documentation/trace/events-nmi.txt43
-rw-r--r--Documentation/trace/events-power.txt31
2 files changed, 74 insertions, 0 deletions
diff --git a/Documentation/trace/events-nmi.txt b/Documentation/trace/events-nmi.txt
new file mode 100644
index 000000000000..c03c8c89f08d
--- /dev/null
+++ b/Documentation/trace/events-nmi.txt
@@ -0,0 +1,43 @@
1NMI Trace Events
2
3These events normally show up here:
4
5 /sys/kernel/debug/tracing/events/nmi
6
7--
8
9nmi_handler:
10
11You might want to use this tracepoint if you suspect that your
12NMI handlers are hogging large amounts of CPU time. The kernel
13will warn if it sees long-running handlers:
14
15 INFO: NMI handler took too long to run: 9.207 msecs
16
17and this tracepoint will allow you to drill down and get some
18more details.
19
20Let's say you suspect that perf_event_nmi_handler() is causing
21you some problems and you only want to trace that handler
22specifically. You need to find its address:
23
24 $ grep perf_event_nmi_handler /proc/kallsyms
25 ffffffff81625600 t perf_event_nmi_handler
26
27Let's also say you are only interested in when that function is
28really hogging a lot of CPU time, like a millisecond at a time.
29Note that the kernel's output is in milliseconds, but the input
30to the filter is in nanoseconds! You can filter on 'delta_ns':
31
32cd /sys/kernel/debug/tracing/events/nmi/nmi_handler
33echo 'handler==0xffffffff81625600 && delta_ns>1000000' > filter
34echo 1 > enable
35
36Your output would then look like:
37
38$ cat /sys/kernel/debug/tracing/trace_pipe
39<idle>-0 [000] d.h3 505.397558: nmi_handler: perf_event_nmi_handler() delta_ns: 3236765 handled: 1
40<idle>-0 [000] d.h3 505.805893: nmi_handler: perf_event_nmi_handler() delta_ns: 3174234 handled: 1
41<idle>-0 [000] d.h3 506.158206: nmi_handler: perf_event_nmi_handler() delta_ns: 3084642 handled: 1
42<idle>-0 [000] d.h3 506.334346: nmi_handler: perf_event_nmi_handler() delta_ns: 3080351 handled: 1
43
diff --git a/Documentation/trace/events-power.txt b/Documentation/trace/events-power.txt
index e1498ff8cf94..3bd33b8dc7c4 100644
--- a/Documentation/trace/events-power.txt
+++ b/Documentation/trace/events-power.txt
@@ -63,3 +63,34 @@ power_domain_target "%s state=%lu cpu_id=%lu"
63The first parameter gives the power domain name (e.g. "mpu_pwrdm"). 63The first parameter gives the power domain name (e.g. "mpu_pwrdm").
64The second parameter is the power domain target state. 64The second parameter is the power domain target state.
65 65
664. PM QoS events
67================
68The PM QoS events are used for QoS add/update/remove request and for
69target/flags update.
70
71pm_qos_add_request "pm_qos_class=%s value=%d"
72pm_qos_update_request "pm_qos_class=%s value=%d"
73pm_qos_remove_request "pm_qos_class=%s value=%d"
74pm_qos_update_request_timeout "pm_qos_class=%s value=%d, timeout_us=%ld"
75
76The first parameter gives the QoS class name (e.g. "CPU_DMA_LATENCY").
77The second parameter is value to be added/updated/removed.
78The third parameter is timeout value in usec.
79
80pm_qos_update_target "action=%s prev_value=%d curr_value=%d"
81pm_qos_update_flags "action=%s prev_value=0x%x curr_value=0x%x"
82
83The first parameter gives the QoS action name (e.g. "ADD_REQ").
84The second parameter is the previous QoS value.
85The third parameter is the current QoS value to update.
86
87And, there are also events used for device PM QoS add/update/remove request.
88
89dev_pm_qos_add_request "device=%s type=%s new_value=%d"
90dev_pm_qos_update_request "device=%s type=%s new_value=%d"
91dev_pm_qos_remove_request "device=%s type=%s new_value=%d"
92
93The first parameter gives the device name which tries to add/update/remove
94QoS requests.
95The second parameter gives the request type (e.g. "DEV_PM_QOS_LATENCY").
96The third parameter is value to be added/updated/removed.